The objectives of this proposal are: 1. to extend our observations of acupunctural and transcutaneous electrically-induced dental analgesia; 2. to fully develop brain evoked potential measures of pain and analgesia for laboratory work; 3. to interrelate these measures with psychophysical Sensory Decision Theory measures; and 4. to further investigate the possible role of endorphins in stimulation-induced analgesia. During the past year we have examined the effects of electrical acupuncture stimulation on brain evoked response to experimental dental pain, and have attempted to determine whether this effect can be reversed by the injection of naloxone, a narcotic antagonist. Our findings support the hypothesis that acupuncture is in part mediated by the release of endorphins. We have also explored the relationship between Sensory Decision Theory and evoked potential methodologies, and our results suggest that these two research methods are tapping a singular perceptual process associated with pain and that the activity of the brain during the perception of laboratory-induced dental pain can be accurately modeled by the theoretical constructs of Sensory Decision Theory. We have also examined the effects of fentanyl, a narcotic analgesic, on the cerebral evoked potential and measured the reversal of this analgesia with naloxone. This provides a better understanding of the relationship between changes in cerebral evoked potential and narcotic analgesia. Our work is contributing to a better understanding of the relationship between changes in brain activity and changes in subjective pain, to growing information on acupuncture analgesia, and to an understanding of the relationship between psychophysics and brain evoked potential work. During the coming year we will continue our work on acupuncture analgesia and place a strong emphasis on further clarifying the relationship between Sensory Decision Theory and evoked potential measures so that this combined methodolgy can be used to study acupuncture analgesia.